Preference factors and isotope effects in the loss of H. (D.) and HCN (DCN) from deuterated pyrazoles upon electron-impact
✍ Scribed by J. Van Thuijl; K. J. Klebe; J. J. Van Houte
- Publisher
- John Wiley and Sons
- Year
- 1971
- Tongue
- English
- Weight
- 311 KB
- Volume
- 5
- Category
- Article
- ISSN
- 1076-5174
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✦ Synopsis
The mass spectra of deuterated pyrazoles show that loss of H' and of HCN from the molecular ion occurs with a very high specificity from the 3(5)-position. For the two processes isotope effects and preference factors have been determined. Metastable ion decompositions involving the loss of HCN from the [M -HI b-fragment indicate that the identity of the hydrogen atoms in this fragment is lost to a large extent.
I N T R O D U C T I O N
IN A PREVIOUS paper on the mass spectra of substituted pyrazolesl a fragmentation scheme was derived for the title compound. In order to study this scheme in more detail the mass spectra of several deuterated pyrazoles have been taken at low resolution. The preliminary results obtained have been published in a note.2
In this paper we present a more detailed study of three fragmentation reactions: two primary processes [MI+* + [M -HI+, [MI+-+ [M -HCN]+-, and the secondary process [M -HI+ + [M -H -HCN]+. * Metastable defocusing has shown that the [M -21-peak in the do compound is caused by this process and not by [MI+. + [M -H2]+..